What is the primary characteristic of polyacrylamide gel electrophoresis (PAGE)?

The primary characteristic of polyacrylamide gel electrophoresis (PAGE) is that it separates molecules based on both their charge and size, which is effectively represented by the correct answer. In PAGE, charged molecules migrate through a polyacrylamide gel matrix when an electric field is applied. The gel acts as a molecular sieve, allowing smaller molecules to move through the gel more easily than larger ones. Additionally, the rate of migration is influenced by the charge of the molecules; charged species move towards the electrode of opposite charge. Therefore, the separation in PAGE is a combined effect of both molecular sieving based on size and movement influenced by charge.

This dual functionality makes PAGE a versatile technique, useful for analyzing a variety of biomolecules, including proteins and nucleic acids. While some methods may focus primarily on size or charge, PAGE incorporates both dimensions to achieve more comprehensive separation.